The present invention is in the technical field of cable guides. More particularly, the present invention is in the technical field of liquid dispenser actuators employing said cable guides.
Certain lever-actuated mechanisms make use of flexible, elongated cables to transfer the point of application of a mechanical force from the actuated lever to a remote location. For example, some hand actuated brake or shifter levers on bicycles and motor bikes take advantage of this transfer of mechanical force to permit riders to apply brakes or shift gears at different parts of the cycle by actuating the levers on the handlebars. Another example of a hand actuator that uses a flexible cable to transfer mechanical force is a liquid dispenser of the type disclosed in U.S. Pat. Nos. 6,299,035 and 7,516,763, the disclosures of which are expressly incorporated by reference herein.
Ideally, flexible cable actuators are designed so that the motion of the cable is largely linear or without significant bends. That is, as the lever actuator is actuated to pull the flexible cable, the cable should be pulled out of its ferrule or housing in generally the same direction as the cable is oriented prior to actuating the lever. Keeping the cable straight and avoiding sharp bends during actuation can improve product longevity, avoiding kinks in the cable to maintain optimal performance, and to reduce the likelihood that the cable will break or fray with continued use.
Unfortunately, design or material constraints may force designers to mount the flexible cable in suboptimal arrangements. For example, in the Prior Art embodiments illustrated in FIGS. 5A-5B, a flexible cable 110 is used in the exemplary actuator 100 to selectively control the flow of liquid from a remote dispensing unit 120. The Prior Art actuator 100 is attached towards a discharge end of a dispensing tube 112, through which a mixture of water and cleaning chemical is dispensed. The appropriate mixture of water and cleaning chemical is provided by the dispensing unit 120 through the use of known proportioning systems such as eductors, aspirators or proportioners. A water shutoff valve 122 is connected to the dispensing unit 120 to control the flow of liquid through the inlet of dispensing tube 112. In order to control the shutoff valve 122 from the discharge end of the dispensing tube 112, the actuator 100 makes use of a flexible cable 110 that is coupled between the actuator 100 and the shutoff valve 122.
The actuator 100 includes a pivotally attached lever 114 that triggers the flow of liquid through the dispensing tube 112. The flexible cable 110 includes a ferrule or housing 116 that is secured to an upstream portion of actuator 100. Meanwhile, the downstream end of flexible cable 110 is secured to the lever 114 such that whenever the lever 114 is actuated between the non-dispensing condition in FIG. 5A and the dispensing condition in FIG. 5B, the flexible cable 110 is pulled through the housing 116 and moves the valve 112 in the dispensing unit 120 into an open, flowing position.
Unfortunately, with exemplary Prior Art actuators 100 of the type shown in FIGS. 5A-5B, actuating the lever 114 (FIG. 5B) to start the flow of liquid through dispensing tube 112 forces the flexible cable 110 to bend at an extreme angle α relative to its original, non-dispensing position (FIG. 5A). Bending over such an extreme angle α does not in itself pose a fatigue problem for the flexible cable 110 as long as the cable 110 is bent over a sufficiently large bend radius. A good rule of thumb for bending steel cable is that the bend radius should be kept to larger than 10 times the cable diameter and preferably over 20 times the cable diameter. In the present example, however, the flexible cable 110 is bent over a hard, sharp edge of the actuator 100 as it extends to the dispensing position (FIG. 5B). In the Prior Art actuator 100, the flexible cable 110 is bent over a small bend radius that is really only on the order of a few cable diameters large. Repeated actuations, and hence repeated over-bending and over-flexing of the flexible cable 110 will ultimately lead to premature fraying, breaking, and failure of the flexible cable 110 and the actuator 100. Water regulatory agencies may require a certain number of actuations before failing. Furthermore, the default failsafe mode should be that the water valve shuts in the event of any failure. However, with the Prior Art actuators, the frayed cable often gets stuck and does not retract completely into the cable housing 116, thereby leaving the water valve 112 open. Therefore, there is a need in the industry for a solution that mitigates the problem of flexible cable failures present in exemplary Prior Art actuators 100 of the type shown in FIGS. 5A-5B.